1) Field of the Disclosure
The disclosure relates generally to pressure sensor systems and methods for aircraft, and more particularly, to an aircraft tipping alarm system and method using fluid pressure measurement on a nose landing gear (NLG) shock strut of the aircraft to signal, when the aircraft has been loaded or unloaded in such a way that it is in danger of tipping back on its tail unless preventative action is taken.
2) Description of Related Art
Key factors in the flight of an aircraft are the weight and balance of the aircraft. The weight of an aircraft is typically supported by retractable landing gear struts. Such landing gear struts contain pressurized hydraulic fluid and nitrogen gas. The pressure within each landing gear strut is related to the amount of weight that landing gear strut is supporting. Large aircraft, such as cargo or freighter aircraft and commercial passenger aircraft, may be supported by a nose landing gear (NLG) shock strut disposed at the front of the aircraft and two or more main landing gear (MLG) struts disposed aft of the aircraft's center of gravity and bilaterally symmetrical to its roll axis. Whether the aircraft is in proper balance or within acceptable limits is also important. An aircraft's pre-flight weight and balance determination is typically made while the aircraft is parked on the ground.
A primary consideration related to an aircraft's weight and balance, particularly for large aircraft that may carry heavy cargo and/or passenger loads, is that the aircraft not be loaded or unloaded in such a way that the change in loading causes the aircraft to tip backward on its tail. If the aircraft tips backward on its tail and comes into contact with the ground, the aircraft may be damaged to an extent that the aircraft cannot be flown without great expense to repair or replace the aircraft, if such repair or replacement is even possible.
Known systems and methods exist for aircraft tip-back alarms. One such known tip-back alarm system uses a sensor having a sensing part and a target part mounted on the nose landing gear (NLG), and detects an extension of the nose landing gear (NLG) beyond a preset tipping threshold, during cargo loading and unloading operations, and sends an alarm signal to ground personnel responsible for the loading of the aircraft. However, such known tip-back alarm system requires the use and installation of an additional structural and mechanical moving system to the aircraft. This may increase the aircraft manufacturing and labor costs and may increase the time and complexity of manufacturing the aircraft.
In addition, another known system and method exists for preventing aircraft tip backs that involves using a harness system that wraps a mechanical harness around the nose landing gear (NLG) of the aircraft to hold the nose landing gear (NLG) down even if the aircraft tips back. However, such known harness system may require an experienced operator to operate the harness system to avoid mishandling of the harness system. Moreover, such known harness system may not be installed or available at places where the aircraft is loading or unloading, such as in an area of conflict where there may not be a cargo airport.
Accordingly, there is a need in the art for an aircraft tipping alarm system and method that is simple to install, use and service, safe, reliable and repeatable, and that provide advantages over known systems and methods.